Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Quantos números Builts tinham números de unidade de 375301-310?
 ###Tabelas: CREATE TABLE manufacturer's_worldwide_ranking (manufacturer's_worldwide_ranking_id AUTO_INCREMENT PRIMARY KEY, Rank INT, Company Name VARCHAR, 2008 Rank VARCHAR, 2009 Revenue VARCHAR, North American Brands VARCHAR, World Headquarters VARCHAR, Country VARCHAR) CREATE TABLE north_carolina_counties_ranked_by_per_capita_income (north_carolina_counties_ranked_by_per_capita_income_id AUTO_INCREMENT PRIMARY KEY, County VARCHAR, Per capita income VARCHAR, Median household income VARCHAR, Median family income VARCHAR, Population INT, Number of households INT) CREATE TABLE fleet_details (fleet_details_id AUTO_INCREMENT PRIMARY KEY, Class VARCHAR, Type VARCHAR, Operator VARCHAR, No. Built INT, Year Built VARCHAR, Cars per Set INT, Unit nos. VARCHAR) CREATE TABLE playing_career_statistics (playing_career_statistics_id AUTO_INCREMENT PRIMARY KEY, Season VARCHAR, League Apps (sub) VARCHAR, League Goals VARCHAR, Cup Apps (sub) VARCHAR, Cup Goals VARCHAR, Total Apps (Sub) VARCHAR, Total Goals VARCHAR) CREATE TABLE playoffs_12 (playoffs_12_id AUTO_INCREMENT PRIMARY KEY, Team 1 VARCHAR, Agg. VARCHAR, Team 2 VARCHAR, 1st leg VARCHAR, 2nd leg VARCHAR)  
SELECT SUM No. Built FROM fleet_details WHERE Unit nos. = 375301-310